1. Field of the Invention
The present invention relates to a synthetic method for generating pure carboxyethyl germanium sesquioxide, and in particular to a chemical method for synthesizing carboxyethyl germanium sesquioxide that yields the carboxyethyl germanium sesquioxide without trace amounts of germanium dioxide or metallic germanium.
2. Description of the Prior Art
Carboxyethyl germanium sesquioxide (organic germanium) has been shown to have chemotherapeutic value. Nakao Ishida, et. al., U.S. Pat. No. 4,473,581 teach that carboxyethyl germanium sesquioxide can induce interferon production in humans. Nagahama teaches in U.S. Pat. No. 4,898,882 that carboxyethyl germanium sesquioxide can provide the human body resistance against the common cold. Asai in U.S. Pat. No. 3,793,455 describes the use of carboxyethyl germanium sesquioxide as an agent for treatment of hypertension. Although carboxyethyl germanium sesquioxide is a well known compound, its molecular structure has been shown to be dependent on the synthetic method employed.
For use as a chemotherapeutic agent, or as a food supplement, it is required that carboxyethyl germanium sesquioxide be pure, free of unwanted and potentially lethal contaminants germanium dioxide and metallic germanium. Many known methods for synthesizing carboxyethyl germanium sesquioxide provide for the production of germanium sesquioxide contaminated with trace amounts of metallic germanium, or germanium dioxide, since these are used as the starting materials. Trichlorogermanium acrylate moieties (trichlorogermanium acroyl chlorides, trichlorogermanium acrylic acids, trichlorogermanium acroleins and trichlorogermanium alkyl acrylates) are the key intermediates common to such known synthetic routes. Entries described by the prior art to the trichlorogermanium acrylate intermediates, utilize methods that require either oxidation of metallic germanium with hydrochloric acid, or reduction of germanium dioxide and, hence, the probability of the presence of trace amounts of unreacted starting material (metallic germanium or germanium dioxide) in the product is significant.
The present invention does not start with either metallic germanium or germanium dioxide, but rather starts with germanium tetrachloride.